As part of the fabrication process for semiconductor devices such as integrated circuits (ICs), these devices typically undergo a heat treating or thermal annealing process following implantation or doping of one or more components of the IC, such as transistors. Annealing may serve several purposes, including physical repair of the silicon lattice structure following doping, and activation of the dopant, resulting in formation of source/drain regions in the transistors. Several different annealing processes have been developed and implemented, but each technique carries with it certain disadvantages.
Rapid thermal annealing (RTA) and diffusion furnace annealing are two processes that may be utilized to anneal semiconductor devices. Both processes typically raise the temperature of the entire silicon wafer on which the device is fabricated for particular period of time using, for example, heat lamps, which radiate the doped wafer surface. However, the RTA and diffusion furnace processes may be time consuming as well as difficult to control, due at least in part to the nature of radiative heating processes.
Laser annealing is a more recent annealing process, which was developed to provide rapid annealing of semiconductor devices, as well as greater thermal control. However, state of the art laser annealing techniques may have certain limitations, and may be in need of improvement. A need exists for an improved method and apparatus for laser annealing.